The best 3 box setup on TLPs (early on in game) but even still a really solid 3 box setup into late game is a Shaman, Shadowknight, and Monk. The monk is selected because it is one of the highest dps classes early on but you could substitute this for a Berserker or any other Melee dps class. The main reason you’d choose a dps class in this setup is that the Shaman provides a lot of melee buffs for haste and attack and would do very little to aid a caster dps.
The tank and healing setup between the Shadowknight and Shaman is very powerful. Although you don’t have complete heals, the shaman has the ability to slow mobs which will significantly reduce the damage your tank takes. The shaman can also provide patch healing and has a heal over time line (Torpor) that when combined with the shadowknights lifetap and leach procs, can make this a very formidable combo for not only leveling but fighting some smaller bosses.
The addition of a monk to this setup gives you an additional puller and a very significant amount of melee dps, not to mention some would argue that Monks are able to take damage like a champ due to their high mitigation, they can almost tank early on (minus the ability to taunt).
Hands down the most powerful in terms of tanking and healing is the Warrior / Cleric setup. With just those two alone you would still lack DPS and slow. Even though the Cleric can put out a lot of healing, the tank takes extra damage without the slow setup you find in the Shaman / SK setup.
However, adding an enchanter for haste, mana regen, slow, and crowd control is just simply a brilliant addition for a 3 box. Not to mention, early on in game the enchanter charmed pets is considered the highest form of DPS in the game (gets questionable after PoP and charm becomes less of a thing) but even enchanters on raids will find it mandatory for some of them to charm pets for fights.
If you dislike the idea of an enchanter you can substitute a Beastlord in the Luclin era and beyond. A beastlord will provide additional DPS, melee buffs, haste, and enemy slows. You’ll also get a pet that can be used as a backup or offtank if things go wrong. Your dps will be somewhat lacking but as far as survivability and what you can achieve in game with this setup, it’s a very powerful 3 box.
It makes it really easy to form your own group and add random players to it when all you need is DPS and utility.
This setup relies heavily on the enchanter charming pets for both tanking and DPS and isn’t really viable past the Planes of Power where other setups might be more beneficial, but early on in game this setup provides a high level of dps, healing, and survivability.
Even though an enchanter charmed pet is very dangerous and chaotic if not done right, the bard could have only a single function of playing a mezz song while targeting the enchanter’s pet. That way if it breaks, the enchanter’s pet would become mezzed and the enchanter would only have to deal with the enemies before re-charming their pet.
This means that you don’t have to skimp on any buffs, you can haste the crap out of your pet and buff it to the core with the safety of knowing if it breaks it won’t make it to you.
Additionally, the bard run speed makes it really easy to get around places. Some people try to substitute a druid in for ports and healing but rest assured, no other class besides a cleric, even after they get their class “complete heals” will have an easy time healing a charmed pet. They seem to take a massive quantity of damage, have a lot of hp, and put out a ton of damage.
Using a druid or shaman to heal a charmed pet that’s tanking will make things extremely tough.
If you’re comfortable with it you could use the bard to play a melody or even use it to add a little melee dps to the group but it’s prime function is to make sure nobody “gets dead”.
Other Mentions
This article is aimed at the best 3 boxing setups which tends to be aimed at ease of use and survivability. It should not be confused with the best 3 classes to play together. If you have someone playing each class you can get away with almost any type of 3 person setup. You could even do something gimmicky like 3x Mage which is neat and will work for a while.
Even boxing 3 mages you get 3 pets to tank, 3 casters to nuke, and if one pet dies you just summon another one. The goal would be to have at least one pet alive and tanking before they all die and the boss or whatever you’re fighting comes for you.
If you’re into gimmicky stuff that requires a bit more attention and skill you could try to 3 box just about anything. I did a druid / enchanter /warrior combo in a classic release and found areas where the druid could charm an animal to go along with the enchanter’s charmed pet and had two pets going. What a fun time that is when both the pets break.
Let me know what your favorite 3 box combo is in the comments below!